13 pnm.c - implements reading and writing ppm/pnm/pbm files, uses io layer.
17 io_glue *ig = io_new_fd( fd );
18 i_img *im = i_readpnm_wiol(ig, -1); // no limit on how much is read
20 io_glue *ig = io_new_fd( fd );
21 return_code = i_writepnm_wiol(im, ig);
25 pnm.c implements the basic functions to read and write portable
26 anymap files. It uses the iolayer and needs either a seekable source
27 or an entire memory mapped buffer.
29 =head1 FUNCTION REFERENCE
31 Some of these functions are internal.
40 #define misspace(x) (x==' ' || x=='\n' || x=='\r' || x=='\t' || x=='\f' || x=='\v')
41 #define misnumber(x) (x <= '9' && x>='0')
43 static char *typenames[]={"ascii pbm", "ascii pgm", "ascii ppm", "binary pbm", "binary pgm", "binary ppm"};
46 * Type to encapsulate the local buffer
47 * management skipping over in a file
59 void init_buf(mbuf *mb, io_glue *ig) {
70 Fetches a character and advances in stream by one character.
71 Returns a pointer to the byte or NULL on failure (internal).
82 if (mb->cp == mb->len) {
84 mb->len = ig->readcb(ig, mb->buf, BSIZ);
86 i_push_error(errno, "file read error");
87 mm_log((1, "i_readpnm: read error\n"));
91 i_push_error(errno, "unexpected end of file");
92 mm_log((1, "i_readpnm: end of file\n"));
96 return &mb->buf[mb->cp++];
101 =item gpeek(mbuf *mb)
103 Fetches a character but does NOT advance. Returns a pointer to
104 the byte or NULL on failure (internal).
114 io_glue *ig = mb->ig;
115 if (mb->cp == mb->len) {
117 mb->len = ig->readcb(ig, mb->buf, BSIZ);
119 i_push_error(errno, "read error");
120 mm_log((1, "i_readpnm: read error\n"));
124 i_push_error(0, "unexpected end of file");
125 mm_log((1, "i_readpnm: end of file\n"));
129 return &mb->buf[mb->cp];
136 =item skip_spaces(mb)
138 Advances in stream until it is positioned at a
139 non white space character. (internal)
148 skip_spaces(mbuf *mb) {
150 while( (cp = gpeek(mb)) && misspace(*cp) ) if ( !gnext(mb) ) break;
157 =item skip_comment(mb)
159 Advances in stream over whitespace and a comment if one is found. (internal)
168 skip_comment(mbuf *mb) {
171 if (!skip_spaces(mb)) return 0;
173 if (!(cp = gpeek(mb))) return 0;
175 while( (cp = gpeek(mb)) && (*cp != '\n' && *cp != '\r') ) {
176 if ( !gnext(mb) ) break;
188 Fetches the next number from stream and stores in i, returns true
189 on success else false.
192 i - integer to store result in
199 gnum(mbuf *mb, int *i) {
203 if (!skip_spaces(mb)) return 0;
205 while( (cp = gpeek(mb)) && misnumber(*cp) ) {
206 *i = *i*10+(*cp-'0');
214 =item i_readpnm_wiol(ig, length)
216 Retrieve an image and stores in the iolayer object. Returns NULL on fatal error.
219 length - maximum length to read from data source, before closing it -1
227 i_readpnm_wiol(io_glue *ig, int length) {
231 int width, height, maxval, channels, pcount;
240 mm_log((1,"i_readpnm(ig %p, length %d)\n", ig, length));
242 io_glue_commit_types(ig);
247 if (!cp || *cp != 'P') {
248 i_push_error(0, "bad header magic, not a PNM file");
249 mm_log((1, "i_readpnm: Could not read header of file\n"));
253 if ( !(cp = gnext(&buf)) ) {
254 mm_log((1, "i_readpnm: Could not read header of file\n"));
260 if (type < 1 || type > 6) {
261 i_push_error(0, "unknown PNM file type, not a PNM file");
262 mm_log((1, "i_readpnm: Not a pnm file\n"));
266 if ( !(cp = gnext(&buf)) ) {
267 mm_log((1, "i_readpnm: Could not read header of file\n"));
271 if ( !misspace(*cp) ) {
272 i_push_error(0, "unexpected character, not a PNM file");
273 mm_log((1, "i_readpnm: Not a pnm file\n"));
277 mm_log((1, "i_readpnm: image is a %s\n", typenames[type-1] ));
280 /* Read sizes and such */
282 if (!skip_comment(&buf)) {
283 i_push_error(0, "while skipping to width");
284 mm_log((1, "i_readpnm: error reading before width\n"));
288 if (!gnum(&buf, &width)) {
289 i_push_error(0, "could not read image width");
290 mm_log((1, "i_readpnm: error reading width\n"));
294 if (!skip_comment(&buf)) {
295 i_push_error(0, "while skipping to height");
296 mm_log((1, "i_readpnm: error reading before height\n"));
300 if (!gnum(&buf, &height)) {
301 i_push_error(0, "could not read image height");
302 mm_log((1, "i_readpnm: error reading height\n"));
306 if (!(type == 1 || type == 4)) {
307 if (!skip_comment(&buf)) {
308 i_push_error(0, "while skipping to maxval");
309 mm_log((1, "i_readpnm: error reading before maxval\n"));
313 if (!gnum(&buf, &maxval)) {
314 i_push_error(0, "could not read maxval");
315 mm_log((1, "i_readpnm: error reading maxval\n"));
320 i_push_error(0, "maxval is zero - invalid pnm file");
321 mm_log((1, "i_readpnm: maxval is zero, invalid pnm file\n"));
324 else if (maxval > 65535) {
325 i_push_errorf(0, "maxval of %d is over 65535 - invalid pnm file",
327 mm_log((1, "i_readpnm: maxval of %d is over 65535 - invalid pnm file\n"));
330 else if (type >= 4 && maxval > 255) {
331 i_push_errorf(0, "maxval of %d is over 255 - not currently supported by Imager for binary pnm", maxval);
332 mm_log((1, "i_readpnm: maxval of %d is over 255 - not currently supported by Imager for binary pnm\n", maxval));
336 rounder = maxval / 2;
338 if (!(cp = gnext(&buf)) || !misspace(*cp)) {
339 i_push_error(0, "garbage in header, invalid PNM file");
340 mm_log((1, "i_readpnm: garbage in header\n"));
344 channels = (type == 3 || type == 6) ? 3:1;
345 pcount = width*height*channels;
347 if (!i_int_check_image_file_limits(width, height, channels, sizeof(i_sample_t))) {
348 mm_log((1, "i_readpnm: image size exceeds limits\n"));
352 mm_log((1, "i_readpnm: (%d x %d), channels = %d, maxval = %d\n", width, height, channels, maxval));
354 im = i_img_empty_ch(NULL, width, height, channels);
356 i_tags_add(&im->tags, "i_format", 0, "pnm", -1, 0);
359 case 1: /* Ascii types */
362 for(y=0;y<height;y++) for(x=0; x<width; x++) {
363 for(ch=0; ch<channels; ch++) {
365 if (gnum(&buf, &t)) val.channel[ch] = (t * 255 + rounder) / maxval;
367 mm_log((1,"i_readpnm: gnum() returned false in data\n"));
371 i_ppix(im, x, y, &val);
375 case 4: /* binary pbm */
376 for(y=0;y<height;y++) for(x=0; x<width; x+=8) {
377 if ( (uc = (unsigned char*)gnext(&buf)) ) {
379 int pc = width-x < 8 ? width-x : 8;
380 /* mm_log((1,"i_readpnm: y=%d x=%d pc=%d\n", y, x, pc)); */
381 for(xt = 0; xt<pc; xt++) {
382 val.channel[0] = (*uc & (128>>xt)) ? 0 : 255;
383 i_ppix(im, x+xt, y, &val);
386 mm_log((1,"i_readpnm: gnext() returned false in data\n"));
392 case 5: /* binary pgm */
393 case 6: /* binary ppm */
394 for(y=0;y<height;y++) for(x=0; x<width; x++) {
395 for(ch=0; ch<channels; ch++) {
396 if ( (uc = (unsigned char*)gnext(&buf)) )
397 val.channel[ch] = (*uc * 255 + rounder) / maxval;
399 mm_log((1,"i_readpnm: gnext() returned false in data\n"));
403 i_ppix(im, x, y, &val);
407 mm_log((1, "type %s [P%d] unsupported\n", typenames[type-1], type));
415 i_writeppm_wiol(i_img *im, io_glue *ig) {
419 mm_log((1,"i_writeppm(im %p, ig %p)\n", im, ig));
422 /* Add code to get the filename info from the iolayer */
423 /* Also add code to check for mmapped code */
425 io_glue_commit_types(ig);
427 if (im->channels == 3) {
428 sprintf(header,"P6\n#CREATOR: Imager\n%d %d\n255\n",im->xsize,im->ysize);
429 if (ig->writecb(ig,header,strlen(header))<0) {
430 i_push_error(errno, "could not write ppm header");
431 mm_log((1,"i_writeppm: unable to write ppm header.\n"));
435 if (!im->virtual && im->bits == i_8_bits && im->type == i_direct_type) {
436 rc = ig->writecb(ig,im->idata,im->bytes);
439 unsigned char *data = mymalloc(3 * im->xsize);
442 static int rgb_chan[3] = { 0, 1, 2 };
445 while (y < im->ysize && rc >= 0) {
446 i_gsamp(im, 0, im->xsize, y, data, rgb_chan, 3);
447 rc = ig->writecb(ig, data, im->xsize * 3);
453 i_push_error(0, "Out of memory");
458 i_push_error(errno, "could not write ppm data");
459 mm_log((1,"i_writeppm: unable to write ppm data.\n"));
463 else if (im->channels == 1) {
464 sprintf(header, "P5\n#CREATOR: Imager\n%d %d\n255\n",
465 im->xsize, im->ysize);
466 if (ig->writecb(ig,header, strlen(header)) < 0) {
467 i_push_error(errno, "could not write pgm header");
468 mm_log((1,"i_writeppm: unable to write pgm header.\n"));
472 if (!im->virtual && im->bits == i_8_bits && im->type == i_direct_type) {
473 rc=ig->writecb(ig,im->idata,im->bytes);
476 unsigned char *data = mymalloc(im->xsize);
482 while (y < im->ysize && rc >= 0) {
483 i_gsamp(im, 0, im->xsize, y, data, &chan, 1);
484 rc = ig->writecb(ig, data, im->xsize);
490 i_push_error(0, "Out of memory");
495 i_push_error(errno, "could not write pgm data");
496 mm_log((1,"i_writeppm: unable to write pgm data.\n"));
501 i_push_error(0, "can only save 1 or 3 channel images to pnm");
502 mm_log((1,"i_writeppm: ppm/pgm is 1 or 3 channel only (current image is %d)\n",im->channels));
515 Arnar M. Hrafnkelsson <addi@umich.edu>